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  • Hanging / suspended Antenna

    Hi

    I was wondering whether it is OK to hang an antenna rather than mount it from the bottom? I was thinking of suspending a good antenna like the LR-1090-N by a piece of string internally in the loft of a bell tower type situation.

    This way it would be close to the roof's outer surface as I would hang it from the highest point, right in the center of the structure.

    It would also be protected from the weather and would not detract from the visual amenity

    Any thoughts?

  • #2
    Should be OK. But not sure if it needs some sort of ground plane, possibly not. I'm not very "expert" at antenna technicalities.
    Mike


    www.radarspotting.com

    Radarspotting since 2005

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    • #3
      Grondplanes help to keep the impedence levels steady (mostly) when used in transmitting situations, but can also help to reflect the signal wave to the antenna to ensure correct reception.

      I am running mine with very small groundplane wires, but tests tend to indicate they are not vital (antenna that comes with MicroADSB has none, but relies on the magnetic contact)
      Posts not to be taken as official support representation - Just a helpful uploader who tinkers

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      • #4
        So any idea what sort of attenuation I can expect from the aerial being inside an octagon shaped structure that is two bricks thick, quite close to the underside of the ceramic roof tiles, versus being outside?

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        • #5
          I suspect you would be limited in the direction of the bricks etc.

          ADSB Is in the Microwave band, (1Ghz) which means objects with moisture levels in them absorb/block the waves.

          Which is why people with antennas on their roof have issues with trees/chimneys in the way. It is ultimately LoS (line of sight) with the exception you might get SOME reflection off objects/around corners slightly
          Posts not to be taken as official support representation - Just a helpful uploader who tinkers

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          • #6
            Originally posted by Bloods View Post
            So any idea what sort of attenuation I can expect from the aerial being inside an octagon shaped structure that is two bricks thick, quite close to the underside of the ceramic roof tiles, versus being outside?
            I'm no antenna expert but with the experience I've had with my setup here I do know that with those bricks in close proximity you'll have some 'blind spots' (and probably a few very large areas where you'll pick up no signal at all). This technology works on line of sight so where you dont have that you'll get no signal.

            I've scoured the net for a link that might help you but nobody wants to commit to recommending locating antennas internally due to the variables (of materials etc) involved. That's why you'll find them stuck out like sore thumbs.

            Regards,
            gregg
            Last edited by fungus; 2012-10-05, 00:22.
            YSSY2/T-YSSY4 [SBS-1 Basestation w/- SSE-1090 SJ Mk2 Antenna (Thanks Delcomp) ] [Uniden UBCD996T w/- 16 element Wideband Discone VHF/UHF Antenna, and tuned 108MHz-137MHz Airband Antenna] [Trialing a home-brew 1090MHz collinear antenna]

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            • #7
              Thanks Oblivian and fungus for your help. I guess I will just have to try it out and see how it goes, locating it internally I mean. It would have to be better than the current situation. I am surrounded by large brick buildings and I have a small magnetic aerial stuck to a piece of 750x750 galvanised sheet sitting near a window. I am getting reliable 50 nm out to 75 nm signals but these would have to be reflections from the brick walls because I don't have any line of sight!

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              • #8
                I trust this might help;

                http://en.wikipedia.org/wiki/Line-of-sight_propagation
                YSSY2/T-YSSY4 [SBS-1 Basestation w/- SSE-1090 SJ Mk2 Antenna (Thanks Delcomp) ] [Uniden UBCD996T w/- 16 element Wideband Discone VHF/UHF Antenna, and tuned 108MHz-137MHz Airband Antenna] [Trialing a home-brew 1090MHz collinear antenna]

                Comment


                • #9
                  Thanks fungus; an interesting article. According to that, line of site in a normal atmosphere from an aircraft at 40,000 ft is about 245 nm although it doesn't specify which wavelength. I have gone cool on the idea of an antenna inside. I have bought a 7 db magnetic with 12 metres of cable and a 20 db amplifier. I am going to put this on a 4 metre pole attached to the chimney. Will be interesting to see how much the big, long, three storey building on one side of our house blocks out rf in that direction.

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                  • #10
                    Originally posted by Bloods View Post
                    Hi

                    I was wondering whether it is OK to hang an antenna rather than mount it from the bottom? I was thinking of suspending a good antenna like the LR-1090-N by a piece of string internally in the loft of a bell tower type situation.

                    This way it would be close to the roof's outer surface as I would hang it from the highest point, right in the center of the structure.

                    It would also be protected from the weather and would not detract from the visual amenity

                    Any thoughts?
                    Get hold of that Antenna Pattern and turn that pattern upside down.

                    You should be able to see if it works like it is designed to.

                    You will get reduction of range.
                    F-WSSS1 - Cats refused to Pee & Pooh on RadarBox - Running a FR24 Receiver & DVB-T Dongle 24/7 to piss off The Chief Thief.

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                    • #11
                      My antenna hangs under the roof beam in a kind of net from short ropes, but upright. I have not seen any degradation.
                      I would not recommend to hang it upside down. That inverts the reception diagram.

                      Andy

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